FR-4, the widely used epoxy glass cloth laminate, is well known for its excellent mechanical strength, flame resistance, and electrical insulation. While most people associate FR-4 with the typical green color seen in printed circuit boards (PCBs), FR-4 is actually available in several different colors, including yellow, white, black, and natural (light green or beige). But what do these colors really mean?
Green FR-4 – The Industry Standard
Most common in PCB manufacturing
Color often comes from the solder mask, not the laminate itself
Standard for consumer electronics and general applications
Offers balanced mechanical, thermal, and electrical properties
Yellow FR-4 – Cost-Effective and Visible
Often used in low-cost electrical insulation applications
Slightly lower aesthetics, but similar core properties
Offers high visibility in production environments
May be used where cost and visibility are prioritized
Black FR-4 – High-End Appearance
Popular in aerospace, automotive, or consumer tech requiring sleek design
Requires carbon black pigments, which may slightly affect flame retardancy
Often customized for structural or decorative insulation applications
White or Beige FR-4 – Optical and Clean Applications
Used in LED lighting, medical devices, or cleanroom environments
Enhances light reflectivity
May have lower Tg (glass transition temperature) unless formulated specifically
Do Colors Affect Performance?
While the base resin and glass cloth largely define FR-4’s performance, color additives or fillers can influence properties slightly:
Flame retardancy might be lower in heavily pigmented materials like black
Thermal conductivity or Tg can vary slightly depending on formulation
Surface resistivity or insulation resistance may be impacted in optical-grade white materials
Tip for Engineers & Buyers
Always check the datasheet, not just the color. Different manufacturers may use similar colors but vary in resin systems, Tg ratings, or compliance (such as RoHS or UL 94V-0).
YILONG supply FR-4 laminates in custom colors and grades to match your technical and visual requirements. Whether you need high-Tg black boards for structural support, or white FR-4 for lighting systems, we can tailor the solution to fit.
For technical specifications or sample requests, contact us at yilong@yilonginsulation.com.
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